All of the Following Statements with Respect to Sealed and Serviceable

All of the following statements with respect to sealed and serviceable bearings are true, EXCEPT:

A) Sealed bearing assemblies are prefilled with lubricant and have integrated grease seals unlike serviceable bearings.
B) In serviceable bearings proper running clearance needs to be adjusted whereas in sealed bearing it is manufactured with clearance.
C) Sealed bearing assemblies do not need periodic maintenance unlike serviceable bearings.
D) Sealed bearing assemblies cannot fail at any time, whereas serviceable bearings can fail.